{ hair analysis it’s everywhere!!!. forensic hair examinations and comparisons are often used as...
TRANSCRIPT
{Hair Analysis
It’s Everywhere!!!
Forensic hair examinations and comparisons are often used as important investigative and associative information
Individual Evidence: evidence which can only be linked to one person
Class Evidence: evidence that can be linked to a group of people
Hair evidence is class evidence
When is it used?
Hair is:a. readily availableb. easily transferredc. difficult to destroy
Why is hair evidence used?
If the source is animal or human Race (sometimes) Where on the body the hair came from Whether the hair was forcibly removed If the hair has been treated with chemicals
If drugs have been taken into the body
What can be determined from hair?
Hair of Infant
Hair of Adult Female
Hair Adult Male
Arm Hair Adult Male
Beard Hair
Cuticle: outside covering of the hair; made of overlapping scales
Cortex: Inner layer made of keratin and imbedded with pigment (color)
Medulla: inside layer running down the center of the cortex
Parts of the Hair
Scales differ between species of animals and are named based on their appearance.
Cuticle Scale Patterns
1. paint clear fingernail polish on a glass slide2. when the polish begins to dry, place a hair on the polish3.when almost dry, lift off the hair and observe the scale imprints
Steps to Visualizing Human Scales
Intermittent or interrupted
Fragmented Continuous Stacked Absent—not present
Types and Patterns of Medulla
Human medulla may be continuous, fragmented or absent
Human Medulla
Determined by measuring the diameter of the medulla and dividing it by the diameter of the hair.
Medullary Index for human hair is generally less than 1/3.
For animal hair, it is usually greater than 1/2.
Medullary Index
Hair can be straight, curly or kinky depending on the cross-section of the hair
What gives hair its shape?
TerminologyAnagen—hair that is actively growing;
lasting up to 5 years
Catagen—hair is not growing; a resting phase
Telogen—hair that is dying and ready to fall out; lasting two to six months
Grows about 0.5 mm per day or 1 centimeter per month; approximately one half inch per month
Hair Growth
{ { Color Length Diameter Distribution, shape
and color intensity of pigment granules Dyed hair has color
in cuticle and cortex
Bleaching removes pigment and gives a yellow tint
Scale types Presence or
absence of medulla
Medullary type
Medullary pattern
Medullary index
Comparing Hairs
Examples of Hair Basics
Cut with Scissors
Cut with Razor
More Hair BasicsNaturally Shed, Buckling and Forcibly Pulled
Naturally Shed
Pulled & Broken
Forcibly pulled with tissue attached
Other Hair DamageFire Damage
Buckling
Burned
Questioned hairs must be accompanied by an adequate number of control samples
a. From victimb. From possible suspectsc. From others who may have deposited
hair at the scene
Control Sample: a group of known materials used for comparison
Collecting Hair
Nuclear DNA- if tissue is still attached from being forcibly removed-traces to individual
Mitochondrial DNA- if not forcibly removed- shows only DNA inherited from the mother- traces to maternal line
DNA from Hair
Hair Toxicology
Toxicology: the study of the nature, effects and detection of poisons and the treatment of poisoning
Advantages of Hair Toxicology:a. Easy to collect and storeb. Externally availablec. Can provide information on the individual’s
history of drug use or poisoning
Collections from all areas of the body can give an accurate timeline of exposure or use
Napoleon died in exile in 1821. By analyzing his hair, some investigators suggest he was poisoned by the deliberate administration of arsenic; others suggest that it was vapors from the dyes in the wallpaper that did him in.
Case Study: Napoleon
On October 3, 1849, Poe was found delirious on the streets of Baltimore, Maryland, "in great distress, and ... in need of immediate assistance", according to the man who found him, Joseph W. Walker.[He was taken to the Washington College Hospital, where he died at 5 a.m. on Sunday, October 7. Poe was never coherent enough to explain how he came to be in this condition. Some believe he was poisoned as a part of a political election corruption scheme
Case Study: Edgar Allan Poe
For additional information about hair and other trace evidence, check out Court TV’s Crime Library at:
www.crimelibrary.com/criminal_mind/forensics/trace/1.html
More About Hair